What we mean by "supplies and equipment" Yumgrinder is that even if you are planning on letting the babies be raised and fed by the parents, you still must ALWAYS be prepared to have to take-over both housing them and feeding them at any moment and any age, from the moment they hatch up through the abundance-weaning process...It's not at all uncommon for parent birds, especially first-time parent-birds like yours, to refuse to feed or lay on the chicks to keep them warm, refuse to feed them at all, actually throw them out of the nest-box, or most-commonly start plucking/mutilating and/or killing the chicks. This can happen at any time with any breeding-pair of birds, and with Budgies it's extremely common...So what this means is the YOU must be completely ready to be able to remove them from the nest-box at any time, be able to house them at the correct temperature immediately (or they'll die quickly if they are younger than 5-6 weeks old and you don't have a homemade Brooder set-up at the correct temperature and ready to go), and be able to feed them proper hand-feeding formula at the proper temperature range (between 104 and 110 degrees F at all times, not one degree colder or hotter) at any moment...
So you have cages and nest-boxes, yes, but do you have a homemade or real Brooder set-up and ready to go that keeps the ambient temperature within the correct ranges depending on the age of the chicks, as I described how to make in my above post? Do you have a canister/bag of commercial hand-feeding formula (Kaytee Exact, Roudybush, etc.), a digital candy/cooking thermometer with a metal probe, unflavored Pedialyte, eye-dropper and oral or disposable Leur-Slip syringes? You must have all of this ready to go BEFORE the first chick hatches in about 19 days or so, because if you don't and the parents refuse to feed or house them, or they become violent and hurt them, there's nothing you'll be able to do to help them...You also need to read-up on the hand-feeding schedules for baby Budgies based on their age, as far as how often they must be fed and about how much per feeding, because this all changes based on their ages just like the ambient temperatures they must be kept at change as their age and feather-growth changes...This isn't optional if you want to be ready to go and not have the chicks die...That's what we're talking about. You can plan on having the parents raise/house/warm and feed their chicks, that's totally fine, but you just need to know that it's quite common for that plan to not work out at all; it may be only one chick they refuse to feed or that they start hurting or kick out of the nest-box, it may be a couple of them, it may be all of them. With first-time parents you have no idea what kind of parents they are going to be. They might be wonderful parents and they might not want to be parents at all and purposely try to kill all of the chicks as soon as they hatch...
This is also the reason why you must block-off the nest-box at least 2-3 times a day after the first chick hatches (when both mom and dad leave the nest-box to eat or poop you use a piece of cardboard or something similar to block-off the entrance to the nest-box so you can look at and if need by remove the chicks)...You'll need to check on each chick several times a day after each one hatches to make sure that it's crop is always full and always emptying correctly after each feeding, and if not, after about 12 hours of seeing a chick's crop empty continuously, that's when you have to make the decision to remove them from the nest-box and put them in your real or homemade Brooder and start hand-feeding them on a strict schedule...And if you see that their crops are not emptying properly after the parents or you are feeding them, then you have to assume they have a yeast infection in their crop, and that's when you have to intervene with either Apple Cider Vinegar or Alka Seltzer tablets mixed with unflavored Pedialyte multiple times until the crop finally empties, then you go back to formula or the parents feeding them....
There a lot to doing what you are planning on taking on, even when you're "planning" on having the parents raise/feed the chicks. Plans don't always go as you envision, and with first-time parent Budgies, as our member Amsterdam found out with his first-time parent Budgies, lots of surprises and unexpected things happen, and then it's either you take-over or they die. So we're just trying to help you prepare to you're fully ready and not scrambling when you find that the parents aren't feeding the chicks and having to come on here, post a question about what's going on and what you need to do, and THEN we're telling you that you have to make a homemade-Brooder to house the chick in and that you have to go and buy a candy/cooking thermometer, hand-feeding formula, Apple Cider Vinegar, Pedialyte, syringes/eye-dropper, etc...It's much easier and much, much more successful for the chicks if you are already fully-prepared with all of the supplies and equipment you may need BEFORE the first chick hatches...That's all, we're just trying to help you in advance...